Light signaling arrangement



Sept. 10, 1935. K. MEYER LIGHT SIGNALING ARRANGEMENT Filed April 13, 1951 K. y figef' Patented Sept. 10, 1935 UNITED STATES PATENT: OFFICE LIGHT SIGNALING ARRANGEMENT Karl Meyer, Berlin-Charlottenburg, Germany, assignor to Orenstein & Koppel Aktiengeselb; schaft, Berlin, Germany Application April 13, 1931, Serial No. 529,770

Germany April 16,1930

' 1 claim.

- Light signals for use in day time, which are preferred to the older semaphore signal on account of greater visibility especially in dull weather and on account of giving the same sig- 5 nals by day and night, are required to operate without any break in order to avoid the signal disappearing entirely when it changes from red to green and therefore being overlooked by the driver of a passing train. It is therefore necessary that the green light should light up before the red light is extinguished and vice versa. Similarly the red light must appear immediately if the green light goes out for'any reason, for example if the lamp burns out. 5 These requirements have been found necessary for safety in railway operation and therefore a number of more or less complicated circuits have been developed. In most cases hese circuits operate with a number of relays which are inter- 20 posed in the circuits of the signal lamps and allow their armatures to drop when there is no current in the winding. Their armature contacts control further circuits and cause the signal lamps to be actuated automatically and imme- 25 diately. The disadvantage of these circuits lies in the use of movable parts and in the wear of the lower contacts. This is found inconvenient when the relays are installed in the open air, as is the case in automatic plants for the block 30 system. The maintenance considerably extends and undesirable interruptions in working have to be taken into account.

Circuits have already been proposed in which the red light is extinguished by a so-called stray 35 transformer by a winding through which the green current flows nullifying the voltage in the red circuit. The disadvantage in this case is the unfavorable ratio between the loads on the red circuit and the green'circuit which prevents any '40 considerable extension of this system. A known circuit operates with a relay which is excited by the green current and when the armature is attracted, simply short circuits the red lamps. The

short circuit current'fiowing through the short 45 circuit contacts is taken into account and is limited by special means to a maximum value. This means, however, fails if the relay is sluggish and does not let its armature fall.

In the following a circuit is described which is 50 suitable for semiand completely automatic light signaling plants and whichcan be employed with advantagewhile the above-mentioned drawbacks are avoided. Its advantage consists'principally in that it only employs apparatus at rest and therefore is extremely certain in operation. It is flows in its full strength through the .F. The red current Jr; in the re pletelyk also characterized'by great simplicity and cheapness together with very high eillciency.

The circuit depends on the fact that hase displaced currents act on one another with inductive or capacitative coupling. 5

The invention is illustrated diagrammatically in the accompanying drawing, in which:

Fig. 1 is a diagrammatic view of a light signaling arrangement in accordance with the invention. 10 Fig. 2 is a vector diagram illustrating the mode of operation of the invention.

Fig. 3 is a view similar to Fig. 1 illustrating a modification of the invention.-

In Fig. 1 the green current branch comprising the choke coil D, the green lamp F, the switch S and the condenser C1, is connected to the phase R-S of a three phase supply RS-T, and the red current branch consisting of the choke coil D which is common to'both circuits, the red lamp H and the condenser 02 is connected to the phase R-T. The absolute magnitudes of the resistances D, C1 and C2 are to be taken as equal or nearly equal to the working resistance of the signal lamps F and H. These lamps take the same amount of power.

If the switch S is closed the green current Jpeen lamp branch is then so reduced that the red lamp H is com extinguished. When the switch S is opened the red lamp H burns brightly.

' The red lamp is extinguished by the inductive voltage drop in the inductance D which is com- -mon'to both branches and which is produced by the green current which is ahead of the red branch voltag R-T. The mode of operation will be seen from the vector diagram shown in Fig. 2.

The current and voltage conditions in-the 40 structural exampleaccording to Figure 1 whichresult when the line clear circuit switch S is closed are shown in Figure 2. E1, E2 and Ea represent the separate phase voltages of the multiphase network, namely a three-phase network according to magnitude and phase position. The values inserted in the diagram were calculated under the assumption that the "blind" resistances ireactances) of the choking coil D1 and the condensers C1 and C: as well as the actual effective resistances of the lamps F and H (in a warm state) are equivalent with respect to their absolute amqun a The total value of the currents flowing over the branches with the signal lamps F and H is characterized by the vector JD. The vector Jn is split up into the two components Jr! and Jr; the current component Jr! is substantially smaller thanthe component Jr and the corresponding current is not suficient to light up the stop lamp. The vector of the voltage en=eo-a induced by the apparent current JD in the choking coll D1 common to both lamp branches is disposed vertically to the vector of the current JD and combined with the vector-of the network voltage Ez=ER -r so that there results for the danger current branch, the voltage according to the vector er-o. This vector is again split up into the two components JHXC2 and JHBH. The voltage component JHBH corresponds to the voltage at the terminals of the stop lamp H. Its absolute value is only a fraction of the absolute value of the network voltage and is not capable of lighting up the stop lamp. Vice versa the vector of the choking coil voltage en in combination with the vector of the phase voltage E1=ESR constitutes the vector of the voltage 65-0 at the line clear current branch, the voltage corresponding to the effective components JFRF being "at the terminals of the line clear lamp F.

If the inductive resistance of the choking coil D1 is so proportioned that in. conjunction with the capacity resistance of the condenser C1 and the effective resistance of the lamp Fit produces a lag of the current JD of 30 relative to the phase voltage Ei=Es-a and moreover, if the absolute value of the inductive voltage drop in the choking coil D1 is equal to the absolute value of the: three-phase voltage, the voltage at the terminals of the stop lamp will be equal to zero, because the .vector eo=eo-a', which is disposed vertically to the vector JD, will coincide with the phase voltage of the vector Ez=Eiz-r so. that the voltage er-o at the terminals of thestop lamp has become equal to zero.' The lamp H is absolutely without current. when the line clear circuit is open, the stop light H shines with full. strength or intensity because the capacity resistance of the condenser C2 inconjunction with the inductive resistance of the choking coil D1 and also the ohmic resistance of the lamp H produces such an apparent resistance that the rated current flows through the lamp H.

It will be understood that the value of the condensers and inductance may vary within certain limits and the following values in numerical terms is given by way of example: 5

The line clear lamp F and the stop lamp B. have each an output of 60 watts and consequently a current of 0.5 ampere with 120 volts and a re-' sistance of 240 ohms. The choke coil in the common branch possesses an apparent resistance of 278 ohms, that is to say, at 50 Hertz an inductivityof 0.89 henry; In the line clear lamp branch, the condenser has a capacity of 24 microfarads with an apparent resistance of 139 ohms and the same applies to the condenser in the stop lamp branch. The voltage of the system amounts to 139 volts with a periodicity of 50 Hertz.

The operation of the system or arrangement will not be affected by replacing thechoking coil with a condenser and the condensers with choking coils (Fig. 3).

What I claim is:

An electric light signaling arrangement having a red lamp and a green lamp, the red lamp being adapted to be lighted when the green lamp is dark and vice versa wherein the signal currents are of different phases comprising a polyphase feed system, conductor means common to the two lamps and connected with one conductor of said system, a second conductor means, said second conductor means including separate connections between said lamps and the remaining conductors of the polyphase feed system, means ineluding an impedance in the common conductor for causing a phase displacement of the voltage and current therethrough, means including an impedance in the separate connections for c'ausing a phase displacement of the voltage and current therethrough opposite to the first mentioned 40 displacement, said impedances being constructed to have such values that in their particular arrangement the current through one of the lamps will be insufi'icient to illuminate it except when the circuit through the other lamp branch is broken or opened.

KARL MEYER. 

